[Dovecot] Best way to migrate from qmail-ldap's autoreply?

[Attila Nagy]

  Hi,

qmail-ldap uses four LDAP attributes for handling autoreplies in 
qmail-local:
- deliverymode (to see whether the autoreply should be send)
- mailreplytext, which is a base64 encoded multiline string*
- mailreplystart and mailreplystop, unix dates

I'm wondering how this could be handled with Dovecot (2.0) in the most 
easier way.
All I could find out so far:
- patching the code
- writing a plugin (it it possible to get these LDAP attributes in the 
LMTPd with a single userdb-lookup and get it from the plugin during a 
new mail event? Any examples?)
- conditionally provide these values to a sieve script and process them 
accordingly (the base64 string and maybe the dates seem to be hard for 
the first glimpse)
the mad stuff:
- using an LD_PRELOAD library, which emulates per user sieve scripts 
according to LDAP lookups (gives a lot more flexibility)
- an LMTP proxy/server, which does all this and forwards the traffic to 
the Dovecot LMTPd/deliver process

* a sample mailreplytext looks like this:
'''%HEADER%
Content-type: text/plain; charset="utf-8"

távol vagyok'''

(of course this is in UTF-8).